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KEY MESSAGES

- Cold tonight, especially northwestern SD where a freeze warning is in effect. Colder air overnight Thursday with widespread freezing temperatures.

- Precipitation chances tonight through Wednesday; heaviest amounts along NE/SD border.

- Breezy Thursday with Wind Advisory (45+ mph gusts) winds possible (~55%).

- Above average temperatures return for the weekend.

DISCUSSION

(This Evening Through Tuesday) Issued at 107 PM MDT Tue Oct 13 2026

Water vapor imagery highlights a closed low centered in southern NV. Further upstream, a strong vort max is located just off the BC coastline with upper level moisture streaming into western Canada. Surface high pressure has settled across eastern MT/western ND with temperatures across the forecast area in the 40s. Low clouds will linger through the afternoon, limiting high temperature potential to the mid to upper 40s for most of the area and low to mid 50s across southern SD. Temperatures are forecast to fall below freezing across portions of Harding, Perkins, and Ziebach counties, particularly closer to the SD/ND border; have issued a Freeze Warning for these counties. Cloud cover may be a limiting factor, however, enough clearing is expected across this area for temperatures to bottom out. South of the warned area, cloud cover is expected to keep temperatures above freezing and limit the potential of frost development.

Chances for precipitation increase Wednesday morning into Thursday as the closed low ejects into the Central Plains. Most of the rain will be confined to areas along and south of I-90 where 0.5-0.75"+ of rain possible for southern Campbell/Weston counties in WY and areas along the SD/NE border.

The northern stream wave that is currently located off the BC coast will swing through southern Canada into the Northern Plains and Upper Midwest late Wednesday into Thursday with a cold front to push through Thursday. As has been the case for a few days, considerable spread remains among deterministic and ensemble guidance regarding the ultimate strength of the winds behind the front. The strongest core of 850-750 mb winds are forecast to remain displaced to our north and east, coinciding with the greatest cold air advection. Forecast soundings highlight potential for Wind Advisory level winds (wind gusts > 45 mph) across northwestern SD through the western SD plains Thursday afternoon. Overall forecast confidence remains low, however. The NBM continues to forecast High Wind strength winds(gusts > 60 mph), which seem overdone and unlikely given the ingredients that will be in place.

Clearing skies and cold air behind the front will result in widespread sub-freezing to freezing temperatures across the forecast area Thursday night into Friday morning. Much warmer this weekend with highs in the 60s and 70s as upper ridging builds over the western half of the US.

AVIATION

(For the 18Z TAFS Through 18Z Wednesday) Issued At 1128 AM MDT Tue Oct 13 2026

Widespread MVFR to localized IFR conditions are being reported around the area this morning. These conditions will linger into the afternoon, slowly trending up from northeast to southwest. That being said, MVFR due to low clouds may linger over portions of the northeast WY Plains, the Black Hills, and SW SD through much of the period given weak flow and lingering low level moisture.

If there is any improvement to high-end MVFR to VFR late this afternoon, conditions will lower again overnight as the next round of rain and moisture streams into the area from the southwest.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Freeze Warning from 2 AM to 8 AM MDT Wednesday for SDZ001-002- 014-078. WY...None.